Staphylococcus aureus (SA) is also called “flesh-eating bacteria”. As a representative of gram-positive bacteria, SA is an important pathogen causing infections in hospitals and communities. SA infection is characterized by acuteness and purulency. Local infection may lead to purulent infections of skins and soft tissues etc, which are unhealed for a long period of time. Systemic infection may result in severe infections such as osteomyelitis, septic arthritis, endocarditis, pneumonia, septicopyemia and the like, and complications. The mortality rate of severe infections and the complications thereof is as high as 20%. Furthermore, exotoxins of Staphylococcus aureus will also give rise to fatal systemic infections, such as food poisoning, scalded skin syndrome and toxic shock syndrome etc.
With wide and long-term use of antibiotics, bacterial drug resistance is increasingly severe. As a typical representative, methicillin-resistant Staphylococcus aureus (MRSA) has become one of the pathogens with the highest hospital infection rate, such as ICU infection, post-operation infection, infection of burn wounds or infection of war wounds etc, since it was first found in 1961. Additionally, MRSA has also become difficulties in clinical treatment, due to its strong pathogenicity, wide transmission, easy outbreak and epidemicity, and multiple-drug resistance, MRSA is also called “the first super bacteria”.
As reported by CDC of the United States, the average annual population of severe MRSA infections is about 90,000 in America, in which about 20,000 patients die. As shown by Report of the National Bacterial Resistance Surveillance of China in 2011: the average clinical detection rate of MRSA is 60%, in which the extensive drug-resistance rate is more than 40%. Currently, MRSA, together with hepatitis B and AIDS, become three major refractory infectious diseases all over the world, and MRSA takes the first place on the list. At present, vancomycin is the last effective medicine for MRSA infections. However, vancomycin-resistant MRSA has already appeared since 1997, and has overspread globally, leading to a challenge of “no effective medicine” for MRSA infections.
Due to the severe challenge of “no effective medicine” for drug-resistant SA infections, “a package plan of 6 policies” has been proposed by WHO in 2011 to address “drug-resistant bacteria”, and priority will be given to research and development of novel products for immunological prevention and treatment, such as inventive vaccines in the future. Accordingly, for effectively controlling the spread of drug resistance of SA and wide SA infections in clinical practice, it is strategically and practically important to study the immunological prevention and treatment of SA infections, and to develop safe, effective and novel gene engineering vaccines for SA.